1. Field of the Invention
The present invention relates to an electron-emitting device, an electron source using the same, and an image forming apparatus serving as a television broadcasting display apparatus, a display apparatus for a video conference system or computer, or an optical printer using a photosensitive drum or the like.
2. Related Background Art
An FE (Field Emission) electron-emitting device which emits electrons from a metal surface by applying a high field of 106 V/cm or more to a metal has received a great deal of attention as one of cold electron sources.
In recent years, flat display apparatuses using liquid crystals have been replacing CRTs in image forming apparatuses such as a display apparatus. The flat display apparatuses are not of self-emission type and require a backlight, and thus demands arise for self-emission display apparatuses.
If an FE cold electron source becomes commercially available, it implements a flat self-emission image display apparatus, contributing to low power consumption and light weight.
A known example of a vertical FE electron source is one disclosed in C. A. Spindt, “Physical Properties of Thin-Film Field Emission Cathodes with Molybdenum Cones”, J. Appl. Phys., 47, 5248 (1976).
A diode structure in which a carbon nanotube is formed close to one terminal of an electrode is described in SID (Society for Information Display) Digest p. 386, 2000. By shifting the electron-emitting member to one terminal of the electrode, a higher field is formed at the terminal than at the center of the electrode. The high-field region formed only at the end of the electron-emitting region narrows the orbit of emitted electrons, obtaining a small electron beam spot.
Also, an electron-emitting device with a triode structure (only section) is proposed in 17th IDW (International Display Workshop) Digest p. 1005, 2000. This structure is shown in FIG. 7. In FIG. 7, an electron-emitting member is formed from a substrate 71, lower electrode (gate electrode) 72, insulating layer 73, upper electrode (cathode) 74, and carbon nanotubes 75. An anode (fluorescent substance) 76 is arranged above the electron-emitting member. The insulating layer 73 is formed from two, SiO2 and polyimide insulating layers. In this device, the lower electrode 72 is set to a high potential to form a high field between the upper and lower electrodes. The field causes the carbon nanotubes 75 formed on the upper electrode 74 to emit electrons, which reach the anode 76 serving as a fluorescent substance.